Researchers at Scripps find evidence that glaciers are tougher than we might think

Global warming has been the hotly debated harbinger of the apocalypse in recent years. Rising ocean levels may put cities or perhaps entire states under salty ocean water while violent storms fueled by an over-warmed atmosphere wrack dry land.

Doom and gloom aside, one naturally occurring effect of raising ocean temperatures is the shrinking of polar ice caps and glaciers. The frozen water returning to the ocean contributes to climbing sea levels and should they disappear into the brine, could probably put most of the eastern seaboard under a pleasant warm ocean surf.

Or maybe they won't. Recently published data from a study done at Scripps Institute of Oceanography at the University of California, San Diego indicates that there may have been glacial growth even during one of the strongest climate warmings in Earth's history, known as the Cretaceous Thermal Maximum.

"Until now it was generally accepted that there were no large glaciers on the poles prior to the development of the Antarctic ice sheet about 33 million years ago. This study demonstrates that even the super-warm climates of the Cretaceous Thermal Maximum were not warm enough to prevent ice growth," explains Richard Norris, professor of paleobiology at Scripps and co-author of the study, titled "Isotopic Evidence for Glaciation During the Cretaceous Supergreenhouse." The study is published in the most recent issue of Science.

The researchers used two independent methods to harvest the data on which they base their claim. Both studies used microfossils from the Cretaceous period and examined them for telltale signs of glacial melt. In one test, the researchers used ocean surface dwelling microfossils and subtracted the ocean surface temperature record from the stable isotope record found in the fossils.

The second method involved bottom-dwelling and near-surface microfossils known as foraminifera. Stable oxygen isotopes were measured in these tests and were found to support the theory of growing icecaps via changing ocean chemistry. Both tests support the conclusion, and fall in line with previous studies which show that sea level fell 25-40 meters at the same time as the ice sheets would have been growing during the Cretaceous.

The catalyst for glacial growth during such a hot period is still a mystery, but some suggestions found in the study are that unusually cool summers could have fostered growth in the mountains of the current Antarctic ice cap, or that increased moisture in the air from the greenhouse affect could have increased winter snowfall in high latitudes and elevations.

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